Boil the water, add herbs and seeds, infuse for 20 minutes. Cool, strain and use as a gargle/mouthwash. If you wish to make up a larger quantity, double or triple the recipe then add 1 tsp of tincture of myrrh as a natural preservative.

A very simple homemade mouthwash:

Wash your mouth with half a glass of warm water containing a teaspoon of table salt.